1. Field of the Invention
This invention relates to a clutch device for an electric motor-driven wheeled vehicle, more particularly to a clutch device with a cam segment and a cam follower to transmit a rotational force of an operating lever to drive a shifter member so as to move a tubular coupler relative to a clutch shaft between coupled and uncoupled positions.
2. Description of the Related Art
Referring to FIGS. 1 to 3, a conventional clutch device 35 is shown to be mounted between an electric motor 25 and a transmitting mechanism 27. The transmitting mechanism 27 includes a transmitting gear 28, bevel wheels 29, differential pinions 20, a differential casing 30, a pin 31, and two bearings 32. The bevel wheels 29 are mounted on two axles 33 which are received in a hollow cylindrical housing 34 disposed on a gearbox 23. The clutch device 35 includes a gear 36 which is received rotatably in the gearbox 23 by means of a bearing 40 and which meshes with a ratchet 26 on an output shaft of the motor 25. A clutch shaft 37 has an outer surrounding wall surface with first and second spline segments 371,372 and a smaller-diameter middle segment 373 therebetween, and an inner surrounding wall surface with an inner spline portion 374 that is in a spline engagement with an outer spline portion 381 of an axle shaft 38. The second spline segment 372 meshes with the transmitting gear 28. The axle shaft 38 is received rotatably in the gearbox 23 by means of a bearing 42. A biasing spring 39 is disposed between the first spline segment 371 of the clutch shaft 37 and an inner side of the gearbox 23. An operating lever 41 is disposed to pass through a cover plate 24 secured on the gearbox 23 to abut against the clutch shaft 37 at the second spline segment 372. The clutch shaft 37 passes through an axial hole in the gear 36. Thus, in a normal state, as shown in FIG. 2, the first spline segment 371 is in a spline engagement with an inner spline portion 361 in the axial hole, thereby transmitting a drive of the motor 25 to the transmitting mechanism 27 via the clutch device 35. As shown in FIG. 3, when the operating lever 41 is operated to move the clutch shaft 37 against the biasing action of the biasing spring 39 such that the middle segment 373 faces towards the inner spline portion 361, the clutch shaft 37 is disconnected from the gear 36.
Since the operating lever 41 is connected directly to the clutch shaft 37 to actuate movement of the latter, and since the biasing spring 39 is required to restore the clutch shaft 37 to its original position, a relatively large amount of force is required to operate the operating lever 41 against the biasing action of the biasing spring 39.
The object of the present invention is to provide a clutch device which can be conveniently and smoothly operated to shift between coupled and uncoupled positions.
According to this invention, the clutch device includes a mounting support which has front and rear ends opposite to each other along an axis, and an inner annular bearing wall that surrounds the axis and that extends between the front and rear ends. A clutch shaft includes a coupled segment and a first spline segment which are disposed opposite to each other along the axis, and which are respectively distal from and proximate to the front end. The coupled segment is adapted to be coupled with an input shaft of a gearbox. A tubular coupler is journalled on and is rotatable relative to the inner annular bearing wall about the axis. The tubular coupler includes a middle segment, a clutching segment, and second spline segment. The middle segment is surrounded by and is shiftable relative to the inner annular bearing wall along the axis. The clutching segment extends from the middle segment forwardly and outwardly of the front end, and includes outer and inner surrounding wall surfaces opposite to each other in radial directions relative to the axis. The inner surrounding wall surface has spline and non-spline regions opposite to each other along the axis, and is disposed to surround and is shiftable relative to the first spline segment between a coupled position, where the spline region is in a spline engagement with the first spline segment, and an uncoupled position, where the non-spline region faces towards the first spline segment in the radial directions, thereby disconnecting the clutching segment from the clutch shaft. The outer surrounding wall surface has a surrounding recess which extends in radial directions and inwardly towards the axis. The second spline segment extends from the middle segment rearwardly and outwardly of the rear end, and is adapted to be maintained in a spline engagement with an output shaft of an electric motor in the coupled and uncoupled positions. A shifter member includes shifting and actuated ends. The shifting end is disposed in the surrounding recess such that the tubular coupler is permitted to rotate relative to the inner annular bearing wall in the coupled and uncoupled positions, and such that the inner surrounding wall surface is shifted between the coupled and uncoupled position by moving the shifting end in an axial direction parallel to the axis. The actuated end is disposed to be externally operable to cause the shifting end to move in the axial direction.